The present invention relates to an apparatus for affixing labels to a moving web and, more particularly, to an apparatus for affixing labels to a moving web in which sudden variation in tension of a label tape caused when a label separated from its base strip is affixed to a traveling web can be relieved and absorbed by an accompanying movement of the label tape in the direction of travel of the web, whereby regardless of variations in the traveling speed of the label tape, labels can be affixed to the traveling web without causing tearing and wrinkling of the labels and the traveling web.
In the printing, web coating or web laminating process, various defects occur. Therefore, it is required to mark instantaneously the positions of defects of a traveling web so that the positions and types of defects can be determined. Unless such marking is employed, the positions and types of defects cannot be found after the web has been rolled. Therefore, a slip or the like recording the positions and types of defects must be prepared by the operator in the printing factory or the like and be sent to the succeeding station of the production line for checking. However, if the slip or the like is lost, it becomes impossible to detect the positions and know the types of defects.
The conventional methods for indicating defects of a traveling web are (1) marking by spraying, (2) marking with ink rolls, felt pens or stamps, (3) inserting a strip of paper, (4) marking with notches, (5) marking with an ink jet and (6) affixing labels. Such methods have their inherent merits and demerits. In the case of (1), the spray nozzle tends to be clogged; ink drips; a portion without defect is marked; and it is difficult to find the positions of defects from the side face when the web is rolled. In the case of (2), marked positions cannot be clearly distinguished and it is impossible to find the positions of defects from the side face of the rolled web. In the case of (3), it is difficult to exactly detect the defects; the defects within the interior of the rolled web cannot be found; and when the rolled web is unrolled, the strip of paper is dropped. In the case of (4), the web is partially cut out and it is impossible to find the defects from the side face of the rolled web. In the case of (5), the ink nozzle tends to be clogged because ink is dried and it is impossible to find the defects from the side face of the rolled web. In the case of (6), the web and the labels tend to be torn off or wrinkled because the traveling speed of the web is not equal to the speed at which the label is pushed forward against the surface of the web. However, this method of affixing labels to the web is considered most advantageous among the above stated defect indicating methods.
In the conventional apparatus for affixing a label to a traveling web, the label must be pushed against the web at the same component traveling speed as the web in the instant of affixing operation. It follows therefore that when the traveling speed of the web varies, the component speed in the direction of the movement of the web at which the label is pushed forward must be varied accordingly. As a result, the labeling apparatus is very complicated in construction.